Conventionally, a resin-sealed electronic device is formed by attaching an electronic substrate on a metal frame and sealing the electronic substrate and the metal frame with a molded resin. On an upper surface of the electronic substrate, various circuit elements and bonding wires are arranged. The bonding wires connect the circuit elements to each other and connect the circuit elements and conductive pins. The upper surface of the electronic substrate is covered with a sheet of rubber, e.g., silicone, for protecting the circuit elements and the bonding wires from a thermal stress of the molded resin.
When a lower surface of the electric substrate is attached on the metal frame with an adhesive agent, a flowing end portion of the adhesive agent flows from the lower surface to a side surface of the electronic substrate, and thereby a fillet part as a flowing-out part of the adhesive agent is provided. When the fillet part covers the whole surface of the side surface, the molded resin cannot hold the side surface directly. Thus, when the resin-sealed electronic device receives a vibration or a thermal stress, the adhesive agent and the molded resin are detached from each other from an edge portion of the upper surface of the electronic substrate, i.e., an end portion of the fillet part. Thereby, the molded resin may not protect the circuit elements and the bonding wires.
To counter the above problem, JP-2000-323624A discloses a semiconductor device that includes a semiconductor chip and a resin substrate. The semiconductor chip is flip-chip mounted on a surface of the resin substrate through an underfill resin. The amount of the underfill resin is determined so that a length of a fillet part formed on a side surface of the semiconductor chip is longer than a distance between the surface of the resin substrate and an upper surface of the semiconductor chip in a direction approximately perpendicular to the surface of the resin substrate. Thereby, when the underfill resin is cured, a warpage of the resin substrate is reduced, and the underfill resin is not detached from the resin substrate.
Alternatively, JP-2001-274303A discloses a semiconductor device that includes a substrate and a heat sink attached to a surface of the substrate through an adhesive agent. The heat sink has an adhesive-agent cavity for preventing an adhesive agent from flowing out from between the substrate and the heat sink.
Either of the above-described semiconductor devices cannot protect circuit elements and bonding wires.